RU2723655C1 - Fuel-operated heating device of vehicle and method of operation of fuel-operated heating device of vehicle - Google Patents

Abstract

FIELD: machine building.SUBSTANCE: invention relates to the machine building. Method (100) of operation of fuel heating vehicle heating device includes reduction (130) of coefficient λ of excess air for combustion between supplied combustion air and supplied fuel in combustion chamber of fuel-operated vehicle heating device for interval Δt time from initial value λ> 1 to the range λ < λ. Lower coefficient λ of excess air for combustion is performed proceeding from continuous operation of vehicle heating device operating on fuel. Vehicle heating device is located before reduction of coefficient λ of excess air for combustion in stable stationary mode of operation. Also disclosed is a fuel-operated vehicle heating device.EFFECT: technical result consists in uniform combustion of deposit in combustion chamber.8 cl, 2 dwg

Description

The present invention relates to a fuel-fired vehicle heating device and its operation method.

A method of operating a fuel-powered vehicle heating device is described, which includes lowering the coefficient λ of excess combustion air between the supplied combustion air and the supplied fuel in the combustion chamber of the vehicle-powered heating device for a time interval Δt from the initial value λ _start > 1 to the range λ <λ _start . The coefficient λ of excess air for combustion, also called the coefficient of excess air or the number of excess air, is a dimensionless parameter between the mass ratio of the supplied combustion air and the supplied fuel. The coefficient λ = 1 of excess air for combustion describes stoichiometric combustion, that is, the complete combustion of the available fuel and the oxygen available in the air for combustion. A value of λ> 1 means a lean mixture of fuel and combustion air, at which more combustion air is supplied than is necessary for complete combustion of the fuel supplied in the same period of time. A decrease in the coefficient λ of excess air for combustion can take place, for example, during continuous operation of a vehicle-powered heating device, and the heating device of the vehicle is located until the coefficient λ of excess air for combustion in a stable stationary mode is reduced. In this stable stationary mode of operation, the coefficient λ = λ _{start of the} excess air for combustion can be constant. An example of a stationary reference value λ _start can be, for example, values between 1.5 and 2.0. The initial values of λ _start can, for example, also vary depending on the rated power of the vehicle’s fuel-fired heating device. For example, the stationary reference value λ _start = 1.8 can be in the case of a vehicle-powered heating device with 15 kW, and the stationary reference value λ _start = 1.7 can be in the case of a fuel-powered vehicle heating device with a rated power 12 kW The range λ <λ _start , to which the coefficient λ of excess combustion air decreases from the stationary initial value λ _start , can be, for example, from 1.1 to 1.4. In particular, the range to which the coefficient λ of excess combustion air decreases from the initial value λ _start is completely higher than λ = 1. Compared with the initial value λ _start, after a decrease in the coefficient λ of excess air for combustion, there is a relatively rich ratio of fuel and air for combustion. This relatively rich mixture of fuel and combustion air is suitable for burning and thus eliminating carbon deposits such as coke or soot that have settled in the combustion chamber. The described method is thus suitable for the regeneration of the heating device of the vehicle, since the combustion chamber is freed from soot, which accumulates over time. In this way, a possible violation of the proper operation of the fuel-powered vehicle heating device due to the formation of soot in the combustion chamber can be prevented. Such malfunctions can be, for example, increased values of the carbon monoxide exhaust gas, increased emission of soot particles and / or higher noise generation during operation of the vehicle’s fuel-fired heating device. Further, carbon deposits in the combustion chamber can also lead to a poor start-up character, that is, to a bad ignition pattern of the vehicle’s fuel-fired heating device, so that in particular during the start-up phase, increased emissions of exhaust gas and soot particles can be caused. This can lead to a complete failure of the vehicle’s fuel-powered heating device, in which the vehicle’s fuel-powered heating device cannot be restarted due to the formation of soot in the combustion chamber.

The above problems are solved or reduced due to the described method.

Preferably, it can be provided that the coefficient λ of excess combustion air is kept in the range λ <λ _start for a time interval Δt in a constant range of values. By keeping the coefficient λ of excess combustion air in a constant range of values over a time interval Δt, a controlled and in particular uniform burnup of soot in the combustion chamber can be achieved. The duration of the time interval can be predetermined on the basis of a specific device, experimentally determined and set for the corresponding type of vehicle-powered fuel heating device. It is also possible to determine the duration of the time interval Δt dynamically based on the amount of soot deposited in the combustion chamber. Conclusions about the amount of soot deposited in the combustion chamber can be made, for example, indirectly through the starting characteristic of the vehicle’s fuel-powered heating device. For this purpose, for example, the temperature and exhaust gas emission can be monitored during the start-up phase of the vehicle’s fuel-fired heating device, and with a less favorable course, an extension of the time interval Δt can be planned during the next upcoming decrease in the coefficient λ of excess combustion air range of values. A constant range of values may be set, for example, around the expected preferably target value λ _ziel . It is possible that instead of a constant range of values, the coefficient λ of excess combustion air is kept at a constant target value of λ _ziel .

Preferably, it can be provided that, at the end of the time interval Δt, the coefficient λ of excess air for combustion returns to the range of final values of the coefficient of excess air for combustion with λ> 1. Thus, the vehicle’s fuel-powered heating device returns after the regeneration is complete, that is, after the burning of the carbon in the combustion chamber is completed, essentially in its original normal stationary mode. The range of final values may preferably include the initial value λ _start . It is possible that the coefficient λ of excess air for combustion returns to the initial value λ _start .

Further, it can be provided that the duration of the time interval Δt is from 2 minutes to 5 minutes. Preferably, the time interval Δt may be 4 minutes. In the above time interval, which is from 2 minutes to 5 minutes, as a rule, complete burnout of soot in the combustion chamber can be expected. The regeneration of the fuel-powered vehicle heating device in this way at the end of the time interval Δt is substantially complete.

Preferably, it may be provided that the amount of combustion air supplied to the combustion chamber is reduced, and / or the amount of fuel supplied to the combustion chamber is increased. By reducing the supplied amount of combustion air and by increasing the supplied amount of fuel, in each case, individually or jointly, the necessary reduction in the coefficient λ of excess combustion air to the range λ <λ _start can be achieved.

Preferably, it may be provided that the amount of combustion air supplied to the combustion chamber and / or the amount of fuel supplied to the combustion chamber is determined depending on the air pressure recorded by the sensor. Due to the change in air pressure, the mass of air supplied to the combustion chamber changes, without the supplied volume of air experiencing a change. By varying the supplied amount of air and the supplied amount of fuel depending on the measured air pressure, this can be compensated, so that the necessary coefficient λ of excess air for combustion is reliably maintained.

Further, it can be provided that a decrease in the coefficient λ of excess combustion air to the range λ <λ _{start is} initiated based on the operating time of the vehicle’s heating device since the last decrease and / or ends on the basis of the air pressure recorded by the sensor. By associating a decrease in the coefficient λ of excess combustion air with the operating time of the vehicle heating device from the time of the last decrease, substantially cyclic regeneration of the fuel-powered vehicle heating device is achieved. During the initial commissioning of the vehicle’s fuel-powered heating device, the time of initial commissioning may be equal to the time of the last lowering, since at this point in time the combustion chamber is free of soot. Further, it can be provided that, regardless of the operating time, at the end of a fixed period of time, for example, once a year, the vehicle’s fuel-fired heating device is regenerated. The end of the reduction based on the recorded air pressure can prevent in higher positions an undesired drop in the expected coefficient λ of excess combustion air below the stated constant value λ _ziel during the reduction. This may occur, for example, if the vehicle, during the reduction of the coefficient λ of excess combustion air, overcomes a greater height difference, for example, on a mountain pass, and due to the concomitant drop in air pressure, less combustion air is supplied to the combustion chamber.

The following describes a fuel-powered vehicle heating device with a control device that is adapted to perform the above method.

The invention described above is now explained by way of example with reference to the attached drawing using a preferred embodiment.

The drawings show:

FIG. 1 is a flowchart of a method of operating a fuel-powered vehicle heating device; and

FIG. 2 is a schematic illustration of a fuel-powered vehicle heating device.

FIG. 1 shows a flowchart of a method of operating a fuel-powered vehicle heating device. The described method 100 starts from start 110. Starting from start 110, it is checked whether the condition is fulfilled, step 120. As a condition, for example, the operating time of the vehicle’s heating device from the moment of the last decrease can be used. Further, the total elapsed time since the last decrease as a condition can also be used. The possible operating time between the two lowering phases can be, for example, from 8 to 30 hours. Most preferably, the operating time can be from 8 to 12 hours, and in turn, 10 hours can be provided as the operating time until in each case the next decrease. The maximum time interval between two lows can be, for example, 1 year. If the condition is not met, step 120 is not, then the method continues from start 110. If the condition is met, step 120 is yes, the method continues to decrease at step 130. Along with those specified in connection with FIG. 1 conditions, that is, the operating time of the heating device of the vehicle from the moment of the last decrease and the maximum period of time from the moment of the last decrease, other conditions that are indicated elsewhere in this description can also be used to initiate a decrease. At step 130, the coefficient λ of excess air for combustion is reduced from the initial value λ _start > 1 to a range of values 1 <λ <λ _start . The initial value of λ _start may be, for example, 1.7 or 1.8. The range of values 1 <λ <λ _start , to which the reduction is carried out, can be, for example, a range from 1.1 to 1.5. Preferably, the reduction can be carried out to a constant value of λ _ziel . λ _ziel may be, for example, 1.2. The reduction of the coefficient λ of excess combustion air can be accomplished, for example, by reducing the supplied combustion air. This can be achieved, for example, by throttling in the air supply region or by reducing the fan speed, the fan supplying combustion air to the combustion chamber. Further, it is also possible to change the supplied amount of fuel, for example, due to the increased flow rate of the fuel pump. Also in this way, the coefficient of excess air for combustion can be shifted to the desired range. The reduction in the supply of combustion air has, in comparison with the increase in the quantity of fuel supplied, the advantage that the thermal power of the fuel-powered vehicle device remains practically constant during the reduction phase, since the amount of fuel supplied remains essentially unchanged. The reduction can be achieved essentially stepwise by directly switching the appropriate means of supply for combustion air and / or for fuel to the required values. Upon completion of the reduction, in step 140, it can be checked whether the initiated reduction phase should end. A suitable criterion is, for example, the expiration of the time interval Δt, which can begin with the start of a decrease in step 130. The duration of the time interval Δt can be from 2 to 5 minutes, preferably 4 minutes. A further criterion for the end of the lowering phase can be the air pressure in the environment of the vehicle’s heating device, since when the air pressure decreases, a smaller mass of air is supplied to the combustion chamber with the combustion air supply means remaining otherwise unchanged. If the lowering phase does not have yet to be completed, step 140 is not, then at the next step 160 essentially only the previous operating state is maintained, that is, the regeneration continues. Based on this, it is again checked whether the lowering phase should be completed, step 140. If the condition for the end of the lowering phase is provided, step 140 is yes, then at the next step 150, the vehicle’s heating device returns to its original mode of operation. This can be done, for example, by increasing the amount of supplied combustion air and / or by reducing the amount of fuel supplied to the original initial values, depending on how the reduction took place before that. Then, from start 110, the method 100 may restart and continue accordingly.

FIG. 2 schematically shows a fuel-powered vehicle heating device 10. The fuel-fired vehicle heating device 10 has a fuel line 12 and a combustion air line 14 through which fuel and, accordingly, combustion air is supplied to a vehicle-fueled heating device. The supplied fuel may be metered by the fuel pump 20 and supplied to the combustion chamber 32. A nozzle 30 is located in the combustion chamber 32, which serves to spray the supplied fuel. The combustion air supplied to the fuel-fired vehicle heating device 10 can be supplied equally to the combustion chamber 32 by means of an air control device 18, for example a fan and / or a throttle device. The atomized fuel and the supplied combustion air form inside the combustion chamber a mixture of fuel and combustion air with a coefficient λ of excess combustion air, depending on the mass of fuel and air supplied per unit time. The coefficient λ of excess combustion air can be determined by a control device 16, which controls the air adjustment device 18 through the control line 22, and controls the fuel pump 20 via a further control line 24. The exhaust gas exhaust of the fuel-powered vehicle heating device is not shown in FIG. 2 definitely, but certainly there. The flue gas exhaust can also have unimagined sensors that can monitor, for example, the flue gas emission values of the vehicle’s fuel-fired heating device, such as the soot number and the load of carbon monoxide. In FIG. 2 depicts a sensor 28 that can detect, for example, ambient pressure in the region of a fuel-powered vehicle heating device 10. The control device 16 can be adapted in particular to perform the above method.

Disclosed in the foregoing description, in the figures, as well as in the claims, the features of the invention may be essential for the implementation of the invention both individually and in any combination.

LIST OF REFERENCE POSITIONS

10 vehicle heating device

12 fuel line

14 combustion air line

16 control device

18 air adjustment device

20 fuel pump

22 control line

24 further control line

28 sensor

30 nozzle

32 combustion chamber

100 way

110 start

120 condition satisfied?

130 lowering

140 ending?

150 return

160 hold.

Claims (8)

1. A method (100) for operating a fuel-powered heating device (10) of a vehicle, comprising lowering (130) the coefficient λ of combustion air excess between the supplied combustion air and the supplied fuel in the combustion chamber (32) of the fuel-powered heating device (10) the vehicle for the time interval Δt from the initial value λ _start > 1 to the range λ <λ _start , and the reduction of the coefficient λ of excess air for combustion is carried out based on the continuous operation of the vehicle’s fuel-powered heating device, and the vehicle’s heating device is to reduce the coefficient λ of excess air for combustion in a steady stationary mode of operation. 2. The method (100) according to claim 1, wherein the coefficient λ of excess combustion air is kept in the range λ <λ _start for a time interval Δt in a constant range of values. 3. The method (100) according to claim 1 or 2, in which at the end of the time interval Δt the coefficient λ of excess air for combustion is returned to the range of final values of the coefficient of excess air for combustion with λ> 1. 4. The method (100) according to any one of paragraphs. 1-3, in which the duration of the interval Δt time is from 2 minutes to 5 minutes. 5. The method (100) according to any one of paragraphs. 1-4, in which the amount of combustion air supplied to the combustion chamber (32) is reduced, and / or the amount of fuel supplied to the combustion chamber (32) is increased. 6. The method according to claim 5, wherein the amount of combustion air supplied to the combustion chamber (32) and / or the amount of fuel supplied to the combustion chamber (32) is set depending on the air pressure detected by the sensor (28). 7. The method (100) according to any one of paragraphs. 1-6, in which the decrease (130) of the coefficient λ of excess air for combustion to the range λ <λ _{start is} initiated based on the operating time of the heating device (10) of the vehicle since the last decrease (130) and / or is completed based on the value recorded by the sensor ( 28) air pressure. 8. The fuel-powered heating device (10) of the vehicle with a control device (16), which is configured to implement the method (100) according to any one of paragraphs. 1-7.

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